Massive multi-input multi-output (MIMO) systems are considered to be key component of fifth-generation (5G) networks [1]}, [2]}, [3]}, [4]}, [5]}, because they are designed to serve many more users with a much higher overall bandwidth [6]}. It has been proved [7]}, [8]} that a massive MIMO system can drastically increase the spectral efficiency of the wireless channel. One of the reasons for this comes from the fact that, as the number of transmitting antennae at the base station (BS) grows, both inter-cellular and intra-cellular interference can be effectively negated [9]}.
